The objective of this project is to understand the structure and function of the active site in cytochrome P450 based mixed-function oxygenases at the molecular level. This will be accomplished by synthesizing iron porphyrins which mimic the active site of cytochrome P450 in various stages of the enzymatic cycle and by fully characterizing these model complexes using Mossbauer, optical, infrared, electron spin, and nuclear resonance spectroscopy, and X-ray diffraction. Model hydroxylation reactions will be developed and their mechanisms studied using reaction kinetics, polymer bonded reagents, intramolecular reaction, and electrochemistry.